In the past a substantial part of preclinical data in allergic diseases has come from studies using rodent models. Cutting edge experiments are now performed using elegant manipulation of the mouse genome with the creation of transgenics and knockouts. As an integral part of this Program Project we propose to develop a Core facility that would facilitate the breeding of sufficient numbers of desired strains of mice that are not commercially available for researchers. The Core will perform three main functions: 1) To breed and provide sufficient number of mice from specific strains that are not commercially available to individual investigators; 2) To provide technical assistance to the investigators with ear punching, bleeding and injecting mice; and 3) To provide service to scientific investigators by assisting with animal care, drug administration, and special procedures. As a centralized facility the core may be able to avoid duplication of effort and will be able to suggest the most cost-effective means of creating mice for specific projects.